The company's waste-management licence required that asbestos be carefully deposited in pre-constructed lanes to contain it and make it easier to cover up. It also stipulated that it should be immediately contained to minimise the risk of any potentially harmful asbestos fibres escaping into the air.

However, the inspectors found that these measures had not been taken, with both bagged and sheet asbestos left exposed on site. No Biffa employees were in the tipping area to undertake or oversee activities.

An enforcement notice was served on Biffa requiring it to immediately comply with its waste-management licence, in terms of covering up any asbestos that could potentially cause harm and ensure waste asbestos was correctly handled in future.

On returning to the site four days later, the officers found asbestos was still not being handled or covered correctly. Biffa staff were still apparently unsure of the correct procedures to follow.

For the Environment Agency, counsel Barry Berlin told Derby Magistrates Court that, as site operator, Biffa was responsible for controlling the deposit and safe handling of the waste it received. Around May 2007, Biffa was receiving brown and white asbestos, and therefore had to adhere to its operational working plan and its waste-management licence.

Pleading guilty, the company was fined £40,000 and ordered to pay £15,400 in costs.

Speaking after the case, Mark Cunningham, a team leader at the Agency involved in the investigation, said: "This persistent mishandling of asbestos plainly created a serious risk of asbestos fibres escaping and seems to have arisen from a combination of poorly trained staff and inadequate management on the part of Biffa".

"I would, however, like to reassure local residents and the public in general that we found no evidence that asbestos escaped from the site."

He added: "The site has since closed to waste disposal but we are still involved in checking that Biffa comply with its long-term responsibility for the after-care of the site and control of landfill gas and monitoring of water quality."

In mitigation, Biffa said it bitterly regretted the incident, staff had since been retrained, and there had been no further incidents before the site was closed in October 2007.